Spray dried agglomerated and densified products are often essential to provide free-flowing material having the physical characteristics necessary for direct compression tableting technique.
Heretofore, free-flowing powder materials were prepared by dusting dried powders with a suitable dusting agent to minimize the development of static electricity and thereby prevent sticking and blocking of the powder flow path. Examples of such dusting agents, which are well-known in the art, include starch, starch esters and silicic acid.
In addition, agglomeration could be achieved by various wet or dry techniques. For example, wet granulation includes both the rotating drum, extrusion techniques and instantizing apparatus.
The formation of free-flowing spray-dried high density agglomerates suitable for direct compression tablet manufacture was, heretofore, not achieved using spray-drying techniques. Spray-drying depends on rapid evaporation rates which are obtained through a high spray surface-to-mass ratio (i.e., fine particle-sized materials). However, if large particulates and agglomerates of the spray feed are formed during the passage through the drying zone, these semi-dried particles tend to adhere on the walls of the spray chamber and thereon accumulate large masses of a wet product. This is especially true with the spray droplets formed from vitamin E emulsions formulated with a gelatin base, vitamin B.sub.2 slurry in a film-forming base and vitamin A emulsion prepared in either acacia or a gelatin base.
It is an object of this invention, therefore, to prepare free-flowing, high density coated agglomerated material suitable for direct compression into tablets using spray-drying techniques.